Generally, special antibiotics for cancer treatments are administered to cancer patients. In the case of patients who require pain management, anodynes are administered to them to reduce pain. Unlike general medicines, administering such special antibiotics or anodynes may lead to a coma or shock death of a patient through overdosing on medical fluid. On the other hand, if the administration amount of such medical fluid is small, it is difficult to achieve the intended purpose of the medical fluid. Therefore, it is very important to appropriately control the administration amount of medical fluid within a permissible range.
To accomplish this purpose, a medical fluid dispenser was devised. The conventional medical fluid dispenser discharges medical fluid so that medical fluid is administered to an administration target, such as a patient, at a constant administration rate. In addition, when a button is pressed, the medical fluid dispenser discharges an additional amount of medical fluid so that the administration rate of medical fluid increases. Medical fluid which is discharged from the medical fluid dispenser is injected into the administration target by an injection unit, such as an injection needle or a catheter. The additional discharge of medical fluid is realized in such a way that a bag made of elastic material, such as rubber or soft plastic, and that has stored the medical fluid therein, is compressed by the force that presses the button.
However, in the conventional medical fluid dispenser having the above-mentioned structure, when the button that has been pressed is released, the additional discharge of medical fluid is interrupted. Thus, the button must be continuously pressed until a desired amount of medical fluid is completely discharged, thereby making it inconvenient to manipulate (in particular, when an injection unit such as a catheter, having a fine passage is used to inject medical fluid, the button must be pressed several times, or for a long period of time, to discharge a desired amount of medical fluid, thus making it more inconvenient to manipulate). Therefore, improvements are required to solve these problems of the conventional technique.